Pol Gen Adul Saengsingkaew said he skipped the meeting with People's Democratic Reform Committee (PDRC) members because PDRC leader Suthep Thaugsuban, who was there, faces an arrest warrant for insurrection.
"If I took part in this meeting and didn't make the arrest, I would be violating Section 157 of the Criminal Code for negligence of duty," Pol Gen Adul said. "I don't want to make the situation worse than it is (by making the arrest)."
The police chief offered the explanation on Saturday while visiting the Police General Hospital, where he met with officers who had been injured in clashes with anti-government protesters on Ratchadamnoen Road last month.
He said the Royal Thai Police had agreed to send Pol Gen Achirawit Suphanphesat, a former deputy chief, to participate in meetings relating to national reform.
The police will be represented at a meeting on Sunday sponsored by the government, after learning that Mr Suthep and top PDRC figures had refused to take part.
Pol Gen Adul added that officers were continuing to keep a close eye on the anti-government protests, and were concerned about potential violence being caused by a third party.